Sulpha-thiazoles



Patented Sept. 18,1945

umrao STATES PATENT OFFICE sULrnA-rnmzows George Newbery, I Hutton Mount, England, as-

sirnor, by mesne assignments, to Merck a Co. Inc., Rahway, N. L, a corporation of New Jersey No Drawing. Original application May'29, 1939,

Serial No. 276,416, now Patent No. 2,362,087,-

. dated November 7, 1944. Divided and this application February 3, 1944, Serial No. 520,951. In Great Britain, Australia, Barbados, Canada, Denmark, Finland, India, New Zealand, Norway, and Sweden, June 3, 1938 1 Claims. (01. 260-2393) This application is a division of Serial No. 276,418, filed on May 29, 1939.

The present invention relates to the preparation of 2-(p-amino-benzene-sulphonamido) de-1 rivatives of thiazole and benzthiazole and their substituted derivatives. many of which have been found to be oi. therapeutic importance, and has for its object the preparation of substituted p-amino-benzene-sulphonamido derivatives of thiazole and benzthiazole of the general formula in which R=hydrogen or an alkyl or aralkyl group and R is a thiazole residue f you s-cn V -c or a benzthiazole residue A,

in which one or more of the hydrogen atoms may be substituted by any of the following groups nitro, amino, 'acylamino, alkyl, aryl, alkoxyl,

X therefore represents an acyl-amino group, a

vnitro group, an azo group linked to an organic radicle, or a halogen, which groups may readily be converted to an amino group, by hydrolysis in the first case, by reduction in the second and third cases or by the action of ammonia in the fourth case.

(B) Derivatives in which R is alkyl or aralkyl may be-obtained by the action of alkyl sulphates on the amino derivatives obtained by any of the methods described in paragraph (A) or by the action of allgvl or aralkyl halides or alkyl sulphates on the intermediate condensation products obtained as described in paragraph (A) and subsequently converting the acylamino group by hydrolysis, the nitro or 920 groups by reduction or the halogen groups by ammonia to compounds of the typ D-NHgCeHcSOzNRR.

(C) In place of the compounds p-XCaH4S02Cl ,the anhydrides (p-XCaHfiOalaO or the bromides p-XCaHrSOaBr may also be used.

The following examples illustrate how the invention may be carried out in practice, but it is to be understood that the invention is in no way limited to the details given in these examples.

- Example 1 50 grammes of 2-amino-thiazole are dissolved in 200 c. as: anhydrous pyridine and a, slight excess (130 grammes) of dry p-acetylaminobenzene-sulphonyl chloride is slowly added.

Some heatis produced and when the mixture begins to cool it is heated for a few minutes to complete the reaction and a large volume of water is added. The precipitated oily 2-(p-ace- 2o tylaminobenzene sulphonamido) thiazole quickly solidifies and is crystallised from solution in warm caustic soda by acidification with 50% acetic acid. The purified product melts at 256 C.

For hydrolysis the product is taken up in a volume of 2N caustic soda equal to 10 times its weight and the mixture heated at 100 C. for an hour. Concentrated hydrochloric acid is then added until the solid at first precipitated has redissolved. The solution is treated with charcoal, filtered and the requisite 2(p-amino benzene sulphonamido) thiazole M. Pt. 196-197 C. is precipitated in a crystalline condition by the addition of sodium acetate.

Example 2 7.5 grammes of 2-amino-4-methyl-thiazolehydrochloride are finely powdered and suspended in 15 c. 0. dry pyridine and 13 grammes of p-bromobenzene-sulphonyl chloride slowly added at a temperature of 30-40 C. After heating for a few minutes on the steam bath to complete the reaction, the whole is poured into a large ex-. cess of water and the product ground with 50% aqueous acetic acid to remove gummy by-prodof 0.880 ammonia, and one twentieth of its weight of cuprous chloride and the mixture heated in a closed vessel at 120 C. On filtration and removal of excess of ammonia by boiling, 2-(paminobenzene sulphonamido)-4-methyl-thiazole separates after the removal of a little gummy impurity, and is purified by one of the methods I 28 grammes of azo-benzine-p-sulphonyl chloride is added to a suspension of 15 grammes of 2-amino-4-methyl-thiazole hydrochloride in 50 c. '0. dry pyridine without external cooling. The mixture is warmed on the steam bath to complete the reaction and poured into water. Crystallisation from 80% acetic acid gives 2-(p-azobenzenesulphonamido) 4-methyl-thiazole M. Pt. 208C.

9 grammes of the azo compound are stirred with 30 c. c. of 2N.NaOH, diluted with warm water till solution is effected, and 9 grammes of Raney nickel catalyst suspended in alcohol added. The mixture is shaken under a pressure of hydrogen of 50 lbs/square inch until the theoretical absorption is attained. The catalyst is removed by filtration and on acidification with acetic acid 2- (p-amino-benzene-sulphonamido) 4 methylthiazoleseparates in a practically pure state. (M. Pt. 239-240 C.)

Example 4 To a solution of 114 grammes of 2-amino-4- methyl-thiazole in 250 c. c. of dry p dine, 250 grammes of p-acetylamino-benzene-sulphonyl chloride is slowly added with stirring at a temperature of 50 -60 C. The resulting reddishbrown syrupy solution is then heated for 1 hour at 100 C. and poured into a mixture of 300 c. c. concentrated hydrochloric acid, 1 litre of water and 500 grammes of ice. The precipitated crude 2-(p-acetylamino benzene sulphonamido) 4-methyl-thiazole is filtered ofi, washed with water and boiled under reflux for 20 minutes with 300 c. c. of concentrated hydrochloric acid diluted with an equal volume of water.

' The solution soobtained is diluted with water and the 2- (p-amino-benzene-sulphonamido) -4- methyl-thiazole precipitated by making alkaline with sodium carbonate. The product may be purified by crystallisation fromv various solvents (such as acetone or methyl-glycol) or by precipitation of the sodium salt by an excess of caustic soda or by saturation with sodium chloride and liberating the pure product by addition of acid. The pure product is a white crystalline powder M. Pt. 240 C.-241 C.

Example 5 To 11.4 grammes of 2-amino-5-methyl-thiazole (dissolved in 25 c. c. of dry pyridine), 24 grammes of p-acetylamino -benzene-sulphony1 chloride is slowly added. The temperature of the mixture Example 6 To 16.5 grammes of 2-amino-4:5-dimethylthiazole hydrochloride in 30 c. 0. dry pyridine is slowlyadded 40 grammes of p-nitro-benzene-sulphonic anhydride, the temperature being kept below 60 C. After heating for a few minutes on the steam bath, water is added and the precipitated 2- (p-nitro-benzene-sulphonamido) -4 5-dimethyl-thiazole recrystallised from 80% acetic acid. The same product M. Pt. 232 C. (with decomposition). results from the action of 24 grammes of p-nitrobenzene s'ulphonyl chloride under similar conditions.

5 grammes of the nitrocompoundare dissolved in 20 c. c. or N.NaOH and the solution added to a ferrous hydroxide paste made by the addition of 10 grammes of caustic soda in 30 c. c. water to a solution of 33 grammes of crystalline ferrous sulphate in 130 c. c. water. After warming for a few minutes to coagulate the. precipitated hydrated ferric oxide, themixture is filtered and the filtrate acidified with 50% acetic acid. The precipitated product is warmed with. 15% hydrochloric acid, some insoluble material removed by filtration and 2-(p-aminobenzene-sulphonamido) -4:'5-dimethyl-thiazole precipitated by the addition of sodium acetate. The product melts at 246 C.

Example 7 by shaking with ether, the solution acidified with water and the 2-(p-acetylaminobenzenesulphonamido)-5-methyl-thiazole which separates is crystallised by solution in hot dilute sodium hydroxide and addition of excess of acetic acid.

After boiling with 10 volumes of 2N sodium hydroxide for 45 minutes acidification with hot 50% acetic acid precipitates 2-(p-amino-benzenesulacetic acid and the precipitated 2(p-aminobenzene-sulphonamido) '4-methyl-5-phenyl-thiazole purified by dissolving in ammonia, treating with charcoal, filtering, and reprecipitating with acetic acid. .The pure product melts at C. (decomp.). I

Example 8 p 17.6 grammes of 2-amino-4-phenyl-thiazole (Traumann Ann. 249, 39) are dissolved in 45 c. c. of pyridine and 23.3 grammes of p-acetylaminobenzene-sulphonyl chloride added with stirring during the course of half an hour. Reaction is completed by heating for 1 hour on the water bath and the still warm reaction mixt e poured into an excess of dilute HCl, the precipitate filtered oil and washed. The product is hydrolysed by boiling with 2N NaOH for 2 hours and the resulting solution made acid with acetic acid. 2-(p-aminobenzene-sulphonamido) -4-phenyl-thiazole is pre cipitated and, after purification by conversion to the sodium salt. liberating the free acid and recrystallising, melts at C.

Example 9 53 grammes of 2-amino-4-methyl-5-hydroxyethyl-thiazole prepared by the condensation of thiourea with 3 chloro-3-aceto-propan-l-ol is dissolved in 50 c. c. of water and 23.3 grammes of p-acetyl-amino-benzene-sulphonyl chloride is added with stirring over a period of half an hour at 15 C. andstirring continued for about 24-48 hours at the ordinary temperature. The product is filtered off, washed with water, and hydrolysed by boiling with 15 times its weight of 35% methane sulphonic acid for 3 minutes. The solution is diluted, neutralised with soda and reacidified with dilute acetic acid. The 2(p-amino-benzenesulphonamido) 4-methyl-5-hydroxy-ethyl-thia-- zole melts when rapidly heated at 141 or by slow heating at I'M-176 C.

Example To 37.2 grammes of 2amino-4-methyl-5-carbethoxy-thiazole (Conrad. Ber. 29, 1896, 1042) suspended in 65 c. c. of dry pyridine at 50 C. are added 48 grammes of p-acetyl-amino-benzene-sulphonyl chloride in small quantities at a time. There is some rise of temperature and complete solution is rapidly obtained. After minutes on the steam bath the product is precipitated by pouring into water, and Purified by grinding with dilute hydrochloric acid and crystallisation from 50% acetic acid. The 2-(p- 'acetylamino-benzene-sulphonamido) 4-methyl- Example 11 21.4 grammes p-acetylamino-benzene-sulphonamide and an equal weight of Z-bromo-benzthiazole are intimately mixed with the addition of 7 grammes dry powdered potassium carbonate and 0.5 gramme copper bronze. The mixture so obtained is stirred for one hour at 200 C. under reflux. The melt is then lixiviated with water and the filtered aqueous solution acidified with excess of acetic acid. The required 2-(p-acetylamino-benzene-sulphonamido) -benzthiazole separates and after crystallisation from acetic acid has M. Pt. 286 C.

Hydrolysis of the acetyl group is effected by boiling the crude acetyl compound with about 10 volumes of concentrated hydrochloric acid and volumes of methanol under reflux. The hydrochloride which separates on cooling is suspended in hot methanol and poured into excess of boiling half saturated solution of sodium acetate. The required 2 (p amino-benzenesulphonamido)-benzthiazole then crystallises in colourless plates M. Pt. 298 C.

Example 12 Example 13 19.4 grammes of 2-amino-6-ethoxy-benzthiazole dissolved in 50 c. c. of dry pyrindine are treated by the slow addition of 24 grammes of p-acetyl-aminobenzene-su1phonyl chloride, the temperature rising to 50-60 C. After warming to complete the reaction the mixture is poured into water and the crude 2-(p-acetylamino-benzene-sulphonamido) -6-ethoxy-benzthiazole purifled by solution in caustic alkali and reprecipitation from the hot solution by excess of acetic acid. After a further crystallisation from 80% acetic acid it has M. Pt. 280-281 C.

The reprecipitated acetyl derivative is suspended in ten volumes of alcohol nd dry hydrochloric acid gas passed in to saturation. On boiling, solution is effected and in a short time the hydrochloride of the :base separates. This is dissolved in methyl alcohol and the alcoholic solution added to an excess 'of sodium acetate in boiling aqueous solution,

'2- (p-aminobenzene-sulphonamido) G-ethoxybenzthiazole separates in colourless prisms M. Pt. 257 C.

Example 14 To 9.75 grammes of 2-amino-6-nitro-benzthiazole suspended in 30 c. c. of dry pyridine are added 12 grammes of p-acetylamino-benzenesulphonyl chloride. Solution is completed by heating on the steam bath. 7 The crude 2-(pacetylamino-benzene sulphonamido) 6 nitrobenthiazole precipitated on addition of water is purified by extraction with 2N sodium hydroxide and acidification of the hot alkaline extract with 50% acetic acid. The purified product forms bright yellow prisms M. Pt. 303 C.

Hydrolysis of the acetyl group ensues on 30 minutes boiling with 10 volumes of 2N caustic soda. The crude amino compound precipitated on acidification is purified by conversion to the hydrochloride by warming with 15% hydrochloric acid. The hydrochlorideis filtered oil, dissolved in excess of ammonia and reprecipitated by addition of acetic acid. The pure Z-(p-aminobenzene-sulphonamido)-6-nitro-benzthiazole so.

obtained melts at 292 C.

Example 15 21 grammes of 2-amino-B-acetylamino-benzthiazole are suspended in 50 c. c. of dry pyridine at 40 C. and 25 grammes of p-acetylamino-ben- 15.0 grammes of 2-amino-benzthiazole is dis-;

(p-amino benzene-sulphonamido) -benzthiazole M. Pt. 298 C.

hydroxide for 40 minutes.

Zena-sulphonyl chloride slowly added. After 30 minutes heating at C. the mixture is added to water and'the precipitated 2- (p-acetylamino-benzene-sulphonamido) -5-acetylamino-benzthiazole crystallised by addition of acetic acid to a. hot solution in dilute caustic soda.- Hydrolysis is effected by boiling with 10 volumes of 2N sodium Acidification with acetic acid then precipitates 2-(p-amino-benzene-sulphonamido) -5-amino-benzthiazole M. Pt. 270 C.

Example 16 20.7 grammes of 2-amino-S-acetylaminobenzthiazole are suspended in 50 c. c. dry pyridine and treated with 23 grammes of p-nitrobenzene-sul- .phonyl chloride at 40-50 C. After warming to its weight of finely divided iron powder and the mixture added to very dilute boiling acetic acid. After making just alkaline with caustic soda and further boiling, ferric oxide is removed by filtration and the filtrate acidified with acetic acid. The crude 2-(p-aminobenzene-sulphonamido) acetylamino-benzthiazole is purified by solution in a large excess of N-hydrochloric acid, followed by addition of sodium acetate. After removal of a less pure fraction while hot, the pure product crystallises out on cooling. It melts at 265 C.

Example 17 the presence of /20 of its weight of cuprous chloride a solid product separates. After crystallisation from methyl alcohol pure Z-(p-amino-benzene-sulphon-methyl-amido) -4-methyl thiazole M. Pt. 206 C. is obtained.

Example 18 23 grammes of 2-amino-5-methyl-thiazole are dissolved in 100 c. c. of pyridine and 46 grammes of p-nitrobenzene-sulphonyl chloride slowly added. [After heating for minutes on the steam bath, the mixture is poured into water and the precipitated 2-(p nitro benzene sulphonamido) -5-methyl-thiazole crystallised by addition of its hot solution in caustic soda to a. large excess of boiling dilute acetic acid. The product M. Pt. 255 C. (dec.) is taken up in N sodium hydroxide (2 mols) and boiled under reflux for 1 hour with an excess of ethyl iodide. The heavy oily layer which separates quickly crystallises and the product 2- (p-nitro-benzene-sulphon-ethylamido) -5- methyl-thiazole after recrystallisation from 80% alcohol meltsat 175.

4 grammes mixed with 8 grammes of fine iron powder is slowly added to 150 c. c. boiling water containing a little acetic acid. The mixture is made alkaline with ammonia and again boiled. Alcohol is then added to the extent of about one quarter of the total volume and the hot mixture filtered from iron oxide. 2-(p-amino-benzenesulphon-ethylamido) 5-methyl-thiazole immediately separates from the filtrate. For purification a few drops of 15% hydrochloric acid are added to a suspension of the base in hot alcohol. The solution so obtained on addition of excess sodium acetate deposits the pure base M. Pt.

Example 19 To a solution of 7.8 grammes of 2 (p-acetylamino-benzene-sulphonamido) -4-methyl thia-.

hours with 100 c. c. of 15% hydrochloric acid and the hydrochloride which separates on cooling decomposed by boiling with dilute aqueous sodium acetate, containing some acetic acid. 2-(p-amino-benzene-suiphon-benzyl-amido) 4 methylthiazole thus obtained after crystallisation from 90% alcohol has M. Pt. 215-216 C.

Example 20 13.5 grammes of 2-(p-amino-benzene-sulphonamido)-4-methyl-thiazole is dissolved in c. c. of 2NNaOH and 6 c. c. of dimethyl sulphate added with mechanical stirring and ice cooling. A further quantity of 2NNaOH is added during the addition to maintain alkalinity together with a little methyl alcohol to break up the solid lumps which tend to be formed towards the end of the addition. The crude 2-(p-aminobenzene-sulphon-methylamido) -4-methy1-thiazole obtained on filtration is recrystallised from 80% alcohol. It melts at 205-206 C.

Example 21 3.5 grammes of 2-(p-acetylamino-benzene-sulphonamido) --benzthiaz0le are taken up in 25 c. c.

v a half hours and the hydrochloride which separates oncooling removed by filtration. This on boiling with equal volumes of alcohol and.i5% aqueous ammonia gives the required Z-(p-aminobenzene sulphon ethylamido) benzthiazole which after crystallisation from alcohol has M. Pt. 209-210 C.

Example 22 3.1 grammes of 2-(p-amino-benzene-sulphonamido) -benzthiazole are dissolved in 25 c. c. of N. NaOH, 2.5 c. c. of diethyl sulphate added, and the mixture stirred vigorously for one hour. After standing, the crystals which separate are removed and washed with dilute sodium hydroxide and with water. Repeated crystallisation from alcohol gives 2-(p-aminobenzene-sulphon-ethylamido) -benzthiazole M. Pt. 209-210 C.

Example 23 8.9 grams of 5-methyl-2-bromthiazole (prepared from the corresponding 2-amino compound by Sandmeyer's method) are intimately mixed with 10 grams of p-nitrobenzene-sulphonamide. 4.5 grams of anhydrous potassium carbonate and 1 gram of copper powder (copper bronze) and the mixture heated for 1 hour at 180 C. and temperature then raised to 200 C. for 15 minutes. When cold the melt is lixiviated with hot water and subsequently with 2N sodium hydroxide- The latter extract is then heated with charcoal, filtered and acidified with acetic acid whereby 5-methyl-2-(pnitro-benzene-sulphonamido) -thiazo1e is precipitated in crystalline condition. .Melting point 254 C. (dec.).

5 grams of the product so obtained is suspended in 50 c. cjof water and dissolved by the addition of 20 c. c. of 2N sodium hydroxide and 11 grams of sodium hyposulphite slowly added with stirring and addition of further 2N sodium hydroxide as necessary to maintain a clear solution. The mixture is heated in the steam bath for a few min- R: is a member of the group consisting of hyin which R1 is a member oi the group consisting of an amino group, an acylamino group, and a nitro group, and in which R: is a member of the group consisting of hydrogen and an alkyl radical, and R: is a member 01' the group consisting of carboxyl and carbalkyloxy radicals.

4. Process for the production of a 2-sulphanilin which R1 is a member of the group consisting of an acylamino group hydrolyzable to an amino group and a nitro group reducible to an amino group, and in which R: is a member 01' the group consisting oi hydrogen and an alkyl radical, and

drogen, aikyl, carboxyl, carbalkyloxy, hydroxyalkyl, and phenyl radicals, which comprises react- .ing -Ri-benzene-sulphonamide, in which R1 has the aforesaid value. with a Z-halo-thiazole of the formula s--c-ai in which R2 and R3 have the aforesaid values and Z is a halogen, in the presence of potassium carbonate and copper.

5. Process for the preparation of 2-(p-aminobenzene-suiphonamido) -thiazole, which comprises heating a mixture of p-acetylamino-benzenesulphonamide and Z-haIo-thiazole in the presence of a mixture of potassium carbonate and copper powder, extracting 2(p-acetylamino-benzene-sulphonamido) -thiazole from the reaction product, and converting the acylamino group in the resulting compound to an amino group by hydrolysis.

6. Process for the preparation of Z-(p-amino- 2 \benzenesulphonamido)-thiazole, which comprises heating a mixture of p-nitro-benzene-sulphonamide and 2-halo-thiazole in the presence of a mixture of potassium carbonate and copper powder, extracting 2-(p-nitro-benzene-sulphonamido) -thiazo1e from the reaction product, and reducing the nitro group in the resulting compound to form an amino group.

7. Process for the preparation of 2-(p-aminobenzene-sulphonamido) -5-methyl-thiazole, which comprises heating a mixture oi p-nitro-benzenesulphonamide and 5-methyl-2-bromthiazole in the presence of a mixture of potassium carbonate and copper powder, extracting 2-(p-nitrc-benzene-sulphonamido)-5-methy1-tl;iazole from the reaction product, and reducing the nitro group in the resulting compound to form an amino group.

GEORGE NEWBERY. 

